Cough is a protective breathing reflex of a human lung system to clear the lung mucus out of the airways. However, many respiratory patients e.g. 70% chronic obstructive pulmonary disease (COPD) patients produce hypersecretion in the airway and are unable to cough effectively the secretion out of the airways because of reduced cough airflow. Excessive lung mucus accumulated in the airway may cause severe problems such as an increasing chance of lung infections, declined lung function, reduced effect of inhaled medicine etc. Thus, it is very necessary to assist the patients to cough lung mucus out of their airways.
Generally, reduction in cough airflow is caused by a combination of decreased lung recoil, airway collapse, muscle decline, airway obstruction and so on. Removal of lung mucus is usually achieved by strong cough airflow. However, most COPD patients can not produce strong cough airflow because of the collapse of the airways. One way of improving a cough process is to use a method or device to prevent cough pressure from releasing rapidly. On the other hand, the device should allow effective cough. A conventional device for assisting a cough can not meet with these two contradictious demands so that it is very difficult for the patients to cough the lung mucus out of the airways.
Thus, there is a need to propose a new device for assisting a cough.